Relationships among early European maize inbreds:: IV.: Genetic diversity revealed with AFLP markers and comparison with RFLP, RAPD, and pedigree data

A set of 51 elite maize (Zea mays L.) inbred lines representative of the early-maturing European flint and dent heterotic groups were assayed for amplified fragment length polymorphisms (AFLP) markers using eight primer combinations. Our main objectives were to (i) investigate the amount of variation for AFLP markers in these materials, (ii) examine the usefulness of AFLP markers for assigning inbred lines to heterotic groups, and (iii) compare the genetic similarity (GS) based on AFLP markers with Malecot's coancestry coefficient Cf) based on pedigree data and with GS estimates based on restriction fragment length polymorphisms (RFLPs) and random amplified polymorphic DNA (RAPD) data. The eight AFLP primer combinations yielded 462 polymorphic bands. GS estimates calculated from AFLP data ranged between 0.38 and 0.77 between unrelated (f = 0) pairs of lines. All flint and dent inbreds showed a smaller mean GS to lines from the other heterotic group than to unrelated lines from the same heterotic group. For lines of mixed origin, the difference in mean GS to flint lines and to dent lines was consistent with the expected genomic proportions from each heterotic group determined on the basis of pedigrees. Principle coordinate analysis of GS estimates resulted in a separate grouping of flint and dent lines. Correlations between f and GS estimates were substantially higher for RFLPs and AFLP markers than for RAPDs. Correlations of GS estimates based on different marker systems were closest between RFLP and AFLP markers both for related (f > 0) and unrelated (f = 0) pairs of flint and dent lines. Results from this study corroborate the usefulness of AFLP markers for (i) assigning inbreds into heterotic groups and (ii) revealing pedigree relationships among lines.